The present invention relates generally to welding apparatus and deals more specifically with a welding apparatus for simultaneously applying a number of spaced apart, parallel welding beads to workpieces to weld them together.
The repetitive welding of workpieces together to fabricate a number of similar assemblies each of which may be a final product or part of another assembly is time consuming and somewhat monotonous to the welding operator. Generally, the fabricated assembly is required in high numbers and its fabrication is often one that can be automated. The repetitive fabrication of such assemblies generally requires the operator to clamp the workpieces together and then apply a welding bead along the workpieces' intersecting edges to form the desired assembly. One assembly, for example, used to form a holding frame for a storm water catch basin grating structure such as the type commonly seen at roadsides to catch storm water runoff, includes mounting tabs extending generally laterally from the sides of the holding frame in a spaced apart, parallel relationship to hold the frame in a recess in the catch basin. Because the grating structure and the frame within which the grating rests is susceptable to large stresses, such as the stress produced by the weight of a vehicle bearing down on the grate and frame, the weld holding the frame and the mounting tab together must be of the highest quality to sustain the repeated stresses caused by the heavy weights. In addition, the welded assembly is subject to attack from other forces such as repeated freezing that causes expansion and contraction of the assembly which may affect the weld. In addition to the time associated with clamping the pieces together in the manual fabrication of such assemblies, the monotony associated with the repetitive welding may introduce variations in the welds from assembly-to-assembly and the variations effect the overall quality and uniformity of the welds and consequently, the structural integrity of the assembly.
It is therefore an object of the present invention to provide a welding apparatus that simultaneously applies a number of spaced apart and parallel welds to workpieces to fabricate a desired assembly.
It is another object of the present invention to provide a welding apparatus wherein the applied welding beads are of a uniform length.
It is a further object of the present invention to provide a welding apparatus that automatically moves the welding arms at a welding station relative to the workpieces to be welded.